The regions of Lombardy and Veneto vote Sunday in referendums on greater autonomy within Italy against the backdrop of the crisis created by Catalonia's push for independence from Spain.

Why the votes and what are they about?

The referendums, initiated by the two regional presidents, are consultative.

Voters will be asked to say Yes or No to the principle of the two regions having greater autonomy under a procedure provided for in Italy's constitution.

A Yes win would allow the regions to begin negotiating the details of more independence with the central government in Rome.

What do the regions want?

In the event of victories for the Yes campaigns, Lombardy President Roberto Maroni and his counterpart in Veneto Luca Zaia, both members of the far-right Northern League, plan to ask for more powers over infrastructure, health and education.

They also want new ones relating to security issues and immigration -- steps which would require changes to the constitution -- and to retain more of the taxes raised in their wealthy, dynamic areas.

Lombardy sends 54 billion euros ($64 billion) more in taxes to Rome than it gets back in public spending. Veneto's net contribution is 15.5 billion ($18 billion). The two regions would like to roughly half those net contributions.

Why the demands?

Veneto (population: 5 million) and Lombardy (10 million) are two of Italy's richest regions and account for 30 percent of GDP.

Their debt per capita is low: 73 euros ($86) for Lombardy, 219 euros ($258) for Veneto, against a national average of 407 euros ($480).

Lower unemployment and welfare costs mean their citizens also cost the state significantly less than the national average.

Maroni and Zaia say this virtuous situation should be rewarded. Constitutional expert Nicola Lupo says the referendums also reflect "a traditional North/South divide and a vision of Rome as corrupt and domineering".

The example of other northern regions that already enjoy greater autonomy is also a factor.

Will Yes win?

Polls put the Yes camp comfortably in front.

"Those who make the effort to vote will probably be voting Yes, particularly as the question asked is relatively consensual," said Lupo.

Turnout is the big unknown. In Veneto, it has to pass 50 percent for the result to be considered valid. There is no quorum in Lombardy but if turnout is under 40 percent the autonomy push is likely to end up being recorded a "minor blip in the history books" said economist Lorenzo Codogno.

As well as the Northern League, the referendums are backed by Silvio Berlusconi's Forza Italia, the populist Five Star Movement, trade union groupings and employers organisations.

Leftwing groups have called on voters to abstain while the ruling Democratic Party has left it up to individuals to decide and several of its big guns, including the mayor of Milan, have said they will vote Yes.

First step to secession?

Maroni insists the vote is no threat to national unity but he wants to reshape relations with Rome in line with a vision of a "Europe of the nations".

Although born as a secessionist party, the Northern League now backs devolution within Italy and emphasises the anti-immigration and anti-euro elements of its platform.

Zaia says any parallels with Catalonia are mistaken or a "crafty" attempt to discourage Yes voters.

"There is no wide separatist sentiment," notes Lupo. But strong Yes results could encourage other regions to go down the same route.

"Although not threatening the unity of the State, this risks setting in motion widespread centrifugal forces within Italy," Codogno said.